Help with port calculations

[Diverse]

I recently purchased a pair of used Tyler Acoustics Taylo Reference Monitors. The ports have come loose due to rough handling during shipping and the 1.75" port cover appears to be choking the 2" port. I also believe the port may not be tuned correctly, since there is a significant spike at a certain frequency, which overpowers other bass frequencies. I'm hoping someone with more experience can provide me with the correct port diameter and length to tune it at the correct frequency. I would like to get a relatively flat frequency response if possible. I have very little experience with speaker design, so any help would be much appreciated.

Woofer: Seas Excel W18E001. (linked to specs)
Tweeter: Scan-Speak Revelator 9900
External dimensions: 23cm x 26.5cm x 46cm
Cabinet construction 2.54cm / 1 inch thick MDF
Internal dimensions: 17.92cm x 21.72cm x 40.92cm
Gross Internal volume: 16.92 Liters
Net Internal volume: ??? (I'm not sure how to determine the net internal volume taking into account the massive crossover, internal brace, port and woofer / tweeter volume)
Current port cut-out diameter: 2.5" / 6.35cm

[jerome69]

See on the specs, tha application note tab.

[Diverse]

Originally Posted by jerome69

See on the specs, tha application note tab.

I have seen the application note tab on the Seas website, however those are for a 25 liter vented enclosure and a 12.8 liter sealed enclosure. I don't believe those will be correct for my 15.93 liter vented box.

[Loren42]

I ran this woofer in LEAP5 and I found the response for the ported version to be rather underwhelming. I feel the enclosure is too small for a vented design.

The port diameter of 1.75" is okay, but making it larger just makes the vent so long it will not fit the enclosure. Making it smaller just creates too much vent noise. I tried various tunings from the mid 30s Hz to 50 Hz and did not see a lot of difference in performance.

However, a sealed box yields a little better bass response. Probably because the vented box size is too small to make the woofer work like it should.

Here is the SPL graph of the sealed version at 100 Watts. The plot is into Half-Space, so you will have a baffle step response to deal with in Full-Space.



Just for kicks, here is the vented version:



I would plug the vent altogether and fill the enclosure with polyfill.

[jerome69]

I wonder if you have the 18WEX001 instead ?

If not, the closed box is the best solution as said.
A middle solution is to make an aperiodic box : fill the vent with polyfill.

[Diverse]

@jerome69
It's definitely a 18WE001, although an older version, with a copper color finished magnet and basket.

@ Loren42
Thank you for your response. I forgot to mention that the enclosure is already filled with poly, I'm not sure if that will make any difference in the calculations, I will try sealing the port and using a sub to compensate for the frequencies below approx 60-70hz.

I agree that the enclosure is small for this driver, I'm considering building a new, larger one.
Just out of curiosity, what does your software show the length needs to be to tune the speaker at 40hz with a 2" port? I'm concerned that a 1.75" port may be too small for the 2.5" cut-out. I've used this online calculator, but I'm not sure how accurate it is. It shows a length of 21.62cm at 40hz with a 15L enclosure.

[bjorno]

Hi,

FYI: As already mentioned:The box is too small for an BR, also the port in respect to the air velocity.

b

[Loren42]

Originally Posted by Diverse

@jerome69
It's definitely a 18WE001, although an older version, with a copper color finished magnet and basket.

@ Loren42
Thank you for your response. I forgot to mention that the enclosure is already filled with poly, I'm not sure if that will make any difference in the calculations, I will try sealing the port and using a sub to compensate for the frequencies below approx 60-70hz.

I agree that the enclosure is small for this driver, I'm considering building a new, larger one.
Just out of curiosity, what does your software show the length needs to be to tune the speaker at 40hz with a 2" port? I'm concerned that a 1.75" port may be too small for the 2.5" cut-out. I've used this online calculator, but I'm not sure how accurate it is. It shows a length of 21.62cm at 40hz with a 15L enclosure.

Port length is 13.95" long. You will need an elbow.

[Diverse]

After some further research, I found that Seas changed the specs for this driver after 2007. I have the older version, for which a spec sheet can be found here. Could someone plug in these revised numbers and see whether it performs better ported or sealed? If ported, what would be the optimal frequency, port diameter / length? thanks =]

[jerome69]

Yes things are changed, better work in a ported box: 17L @ 36Hz
Port 2" Length = 9" but the diameter is not enough, you will have too much turbulence. D 2.5" L 15" is better but the length